The telecommunications industry is currently undergoing a transformation from a traditional circuit switched network, which was originally designed and optimized for carrying voice telephony traffic, to packet based networks which will be capable of efficiently supporting both voice and data communications.
A next generation network (NGN) is a packet-based network that employs new control, management, and signaling techniques to provide both narrow-band voice telephony services and broadband multimedia services.
NGNs have been described in several standardization bodies, defining network models and an architecture of the new network. These standardization bodies include 3GPP with IMS (IP Multimedia Subsystem), ETSI with TISPAN (Telecoms & Internet Converged Services & Protocols for Advanced Networks) and MFS who are defining the architectural aspects.
The general idea behind NGN is that all information is transmitted via packets, which are labeled according to their type (data, voice, etc) and handled differently for Quality of Service (QoS) and security purposes by traffic management equipment. Media gateways are devices, which are used at the boarder between an NGN and a PSTN (public switched telephone network).
In next generation networking, different protocols for voice transmission are in use today. These include G711, G729, G723, G726, and AMR (Adaptive Multi-Rate) and all use different voice codecs. At the interconnection point between different NGNs, gateways are hence required which perform transcoding to convert between different protocols used in the peering networks. Such gateways are commonly referred to as session boarder controllers (SBC). Standardization has divided the SBC into two part, ie a media SBC for traffic conversion and a signaling SBC for conversion of signaling protocols.
The conversion as such is typically carried out with the aid of Digital Signal Processors (DSPs). A DSP is a specialized microprocessor specifically designed for real-time digital signal processing. DSPs are however relatively expensive and will considerably increase the price of the media gateways. It is hence desirable to utilize DSP resources economically.
Today, existing gateways do either perform 100% transcoding as for example between mobile and fixed networks and are hence equipped with full 100% DSP capacity, or do not perform transcoding at all.
It might be desirable to provide a media session boarder controller with less than 100% transcoding capabilities. This can however lead to a situation where idle links are blocked when all installed DSP capacity is busy. In this case, no further service will be possible anymore, even service that would not require transcoding. This can be unacceptable in certain cases where for example peering network providers or customers have configured a number of links but the DSP resources are not able to process the amount of parallel sessions.
It is therefore an object of the present invention to provide a method and related media session boarder controller for a next generation network which does not require 100% transcoding resources but which avoids situations in which further service is blocked because of exhausted DSP resources.